Lecture nine: control of movement

Question 1

what are Extrafusal Muscle fiber?

Answer 1

<2muscles attached to the bones by tendons, for movement”

Activated by alpha motor neurons

Question 2

Intrafusal muscle fibers

Answer 2

set makes muscle spindle
Wrapped by afferent fibers (sensory endings)
But also: activated by gamma motor neurons
For detection of muscle length
For detection of muscle length

Question 3

Golgi tendon organ

Answer 3

for detection of change in muscle tension

Question 4

Pacinian corpuscles and free nerve endings

Answer 4

for detection compression of muscle (during contraction) and waste products

Question 5

What does Myofibrils consist of?

Answer 5

Myofibrils in extrafusal fibers consist of Actin and Myosin

Question 6

mechanism of muscle contraction

Answer 6

1. Myosin (yellow) binds actin (pink).
2. Myosin heads fall over and slide forward along the actin.
3. Myosin heads release
4. Rest condition

Question 7

What is the Monosynaptic stretch-reflex?

Answer 7

1. weight falls on hand
   2.detection
   muscle extension
2. reflexive muscle contraction

Question 8

What is the Polysynaptic inhibitory-reflex?

Answer 8

Inhibition α neuron by Golgi tendon organ
prevents excessive tension on muscle

Lift more by sedating Golgi tendon organs

Question 9

Explain the function of monosynaptic stretch

reflexes

Answer 9

Monosynaptic stretch responses function to control limb
movements when weight is applied or removed quickly
and to maintain upright posture.

Question 10

Contrast the structures and function of

polysynaptic reflexes with monosynaptic reflexes:

Answer 10

Monosynaptic reflexes include a single synapse involved
in simple reflexes like the patellar reflex. Polysynaptic
reflexes involve multiple synapses involved in more
complex reflexive behavior, such as inhibiting a
withdrawal reflex. Polysynaptic reflexes contain at least
one interneuron between the sensory neuron and the
motor neuron.

Question 11

Corticospinal paths
Lateral group:
for independent limb movements:

(very importat sh$t)

Answer 11

Rubrospinal tract (via red nucleus)
lower arms, hands (not fingers)
lower legs, feet (not toes)

Corticobulbar tract
neck, face, eyes, tongue

Lateral corticospinal tract
arms, hands, fingers
legs, feet, toes

Question 12

Rubrospinal tract

Answer 12

Rubrospinal tract (via red nucleus)
lower arms, hands (not fingers)
lower legs, feet (not toes)

Question 13

Corticobulbar tract

Answer 13

neck, face, eyes, tongue

Question 14

Lateral corticospinal tract

Answer 14

Lateral corticospinal tract
arms, hands, fingers
legs, feet, toes

Question 15

What is the Ventromedial group for:

Answer 15

for balance (body posture) and walking
and controlled via nuclei in brainstem

Question 16

Ventral corticospinal tract

Answer 16

Body posture: trunk and upper legs

Question 17

tectospinal tract

Answer 17

Orientation: trunk and head/eye movements

Question 18

vestibulospinal tract

Answer 18

Body posture: trunk and legs

Question 19

reticulospinal tract (1: lateral PRF)

Answer 19

Walking: bending legs

Question 20

reticulospinal tract (2: medial MRF

Answer 20

Walking: stretching legs

Question 21

reticulospinal tracts for autonomic functions:

Answer 21

: muscle tension, breathing, coughing, sneezing

Question 22

The lateral group consists

of the

Answer 22

the corticospinal tract, the corticobulbar tract, and the
rubrospinal tract. This system is primarily involved in control
of independent limb movements, particularly movements of
the hands and fingers.

Question 23

The Cerebellum 

Answer 23

motor coordination

Question 24

Cerebellum: damage

lateral system

Answer 24

problems with timing (agonist-antagonist) muscles results in tremor in particular at the endpoint of movements

Question 25

What is the SMA

Answer 25

SMA: Supplemantary Motor Cortex SMA: in particular for planning movement sequences Neuron specifically active during “pull-push” sequence (not during “push”, “pull”, “turn” only, or during other sequences such as: “Push-Pull”)

Question 26

PMC

Answer 26

Premotor Cortex: planning movements

Question 27

Damage to parietal lobe leads to

Answer 27

Apraxia (no action) | inability to carry out complex actions without pareses

Question 28

What are the symptoms of 1: Limb apraxia after damage to left parietal lobe

Answer 28

Use wrong body parts Correct body parts but incorrect movement Wrong sequence of movements Especially during: Imitating actions Demonstrating actions with tools

Question 29

Constructional apraxia

Answer 29

Constructional apraxia after damage to right parietal lobe Problems with copying figures Problems with building larger objects from smaller elements In fact more a visual problem: difficulty with combining the individual elements to recognize a whole object

Question 30

Explanation left-right difference:

Answer 30

Left parietal: representation own body (limb apraxia) Right parietal: representation outside world (constructional apraxia)

Question 31

Basal Ganglia:

Answer 31

motor gating

Question 32

parts of the basal Ganglia

Answer 32

1. Caudate nucleus 2. Globus pallidus 3. Putamen

Question 33

where do informations for caudate nucleus and putamen come from>>?

Answer 33

Caudate en Putamen: input from primary motor and somatosensory cortex and substantia nigra

Question 34

where do informations from globus pallidus go?

Answer 34

output to motor nuclei brainstem and primary motor and premotor cortex and SMA (via thalamus)